1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Intensity of the incident light

  1. Apr 5, 2009 #1
    1. The problem statement, all variables and given/known data

    Unpolarized light is incident on a system of three polarizers. The second polarizer is oriented at an angle of 33.0° with respect to the first and the third is oriented at an angle of 45.0° with respect to the first. If the light that emerges from the system has an intensity of 2.3 W/m2, what is the intensity of the incident light?

    2. Relevant equations

    Iout=Iincos2[tex]\theta[/tex]

    3. The attempt at a solution

    I know that after I0 passes through the first polarizer, it is 1/2I0. After it passes through the second, I thought it would be 1/2I0cos2(33), and after it passes through the third, 1/2I0cos2(33)cos2(45).
    This would all equal 2.3, which I was given.
    So I set up my final equation as:
    1/2I0cos2(33)cos2(45) = 2.3, or
    I0= 2.3 / (1/2cos2(33)cos2(45).

    I solved and got 13.08, but that is incorrect. Can anyone offer any insight? Thanks.
     
  2. jcsd
  3. Apr 6, 2009 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    For the third polarizer, use the angle between it and the second polarizer.

    45° is the angle between the third and first polarizer.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook